1. Field of the Invention
The present invention relates to a bilge pump activator switch for use aboard vessels. More particularly, the present invention relates to a bilge pump activator switch which senses the true water level in the bilge area asa function of the water level in its housing, and upon a predetermined water level being reached activates, by means of a mercury switch element, an electrical circuit including a bilge pump, the mercury switch and a battery.
2. General Background
In the marine industry it is essential that bilge pumps be activated and deactivated as a function of a predetermined bilge water level. It is desirable that this predetermined water level be indicated accurately, independent of list of the vessel, and automatically without an individual being required to monitor the bilge water level.
Several attempts have been made in the known art to develop an automatic bilge pump activator switch.
A typical known art device would have a float which would rise with the water level and tilt a mercury switch, thereby completing a circuit including a bilge pump, the mercury switch and a battery. This method is less than acceptable as listing of the vessel can offset the tilt of the mercury switch and maintain the bilge pump-mercury switch-battery circuit open, and thus the bilge pump "off", even though the water level has reached a dangerous level requiring pumping. At the other extreme, listing alone can induce the tilt of the mercury switch and prematurely close the bilge pump-mercury switch-battery circuit, and thus activate the bilge pump, even though the water level remains at an acceptable level; or the listing can induce tilt and maintain an already closed circuit closed and thus the pump "on" even though the bilge water is at an acceptable level and the pump should deactivate thereby causing damage to the bilge pump. It can also be understood therefore, that the listing of the vessel can cause both the premature and delayed opening and closing of the mercury switch and hence unwanted and erratic activation and deactivation of the bilge pump, thus reducing pumping time and expending rapidly the life of the battery--the "on-off-on-off . . . " problem.
Further known art devices use float mechanisms and mercury tilt switches which pivot about lines connected by pins, brackets or other mounting devices which offer resistance and can become fouled with grease or oil which results in restriction and eventually sticking of the float.